The present invention relates to a method for the joining of tubular parts in a heat exchanger that are inserted into each other, as well as to a tool for practicing the method.
German Offenlegungsschrift No. 23 32 241 describes a process for the joining of tubes that are inserted into each other, whereby the telescopically inserted tubes are deformed elastically by means of a shaping ring so that a sealing pressure acting in the radial direction is obtained in the area of the shaping ring between the inserted tube ends. The shaping ring has an orifice, the diameter of which is at least in one portion smaller than the diameter of the outer tubular part and is sufficiently strong to deform the tubular ends elastically in the radially inward direction. When the shaping ring is released, the tubular ends regain their original shape elastically and are thereby separated from each other.
Tube joining methods of this type are not suitable for large scale industrial production, since the application and the compression of each individual shaping ring is highly labor intensive and, consequently, expensive. Furthermore, the shaping element must remain in the area of the tube joint or otherwise the joint will separate. This has the disadvantage, especially in the case of heat exchangers for automotive vehicles, that the shaping elements remaining around the tube joint increase the weight of the heat exchanger, contrary to the requirements of the car manufacturer to reduce the weight.